Sharpening-tool



No. 6I8,880. Y Patented Feb. 7, |899. F. A. HUMFHREY.

SHARPENING'TUDL.

'ation med Feb. 189s.)

v (No Model.)

i! Il Nrrn STATES PATENT (")Fiultv FRANK A. HUMPHREY, OF WORCESTER, MASSACHUSETTS.

SHARPENlNG-TOOL.

SPECIFICATION forming part of Letters Patent No'. 618,880, dated February '7, 1899,

Application filed February 7, 1898l Serial No. 669,299. (No model.)

To all whom t may concern..-

Be it known that I, FRANK A. HUMPHREY, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Sharpening-Tool, of which the following,together with the accompanying draw- Y ings, is a specification sufficiently full, clear,

' els, and capable of effecting its work in an expeditious and satisfactory manner. I attain these objects by a sharpening-tool having the peculiar construction illustrated in the drawings, wherein- Figure l is a perspective view showing'the outer face. Fig. 2 is a perspective view of the inner face. Fig. 3 is a perspective side view. Fig. 4. is a longitudinal central section at line w w on Fig. 2. Fig. 5 is a transverse section at line X X, Fig. 1. Fig. 6 is a cross-section of the smaller end at line Y Y, Fig. 1, corresponding to that of Fig. 5. Figs. 5 and 5b show modifications in cross-section that I employ as equivalent within the scope of this invention, and Figs. 6 and 6b show crosssections of the smaller end respectively corresponding to the formsv of sections Figs. 5a and 5b.

My invention consists in a sharpening-tool or article for the 'purpose set forth formed from gritty or abrasive material-such as corundum, emery, comminuted quartz, whetstone, or other suitable grit substance natural or artificial in its compound-and comprising in character a longitudinally-tapered transversely-crescent-shaped rigid body, as hereinafter specifically explained and as defined in the summary.

Referring to the drawings, A denotes the slip or body, preferably formed solid or of similar substance throughout its mass and essentially shaped as shown, with a larger end B and a smaller end O, between which the body extends with longitudinally-right-lined semiconical or tapering form with a direct uniform taper, while having a transverse shape or cross-section of substantially crescent shape at any portion or interval of its length, (as denoted by the section view on line XX and Y Y,) the outer side presenting a straight conoidally-tapering transverselyconvex surface 3 and the inner side presenting a straight conoidally tapering transversely-concave surface 5. The two edges or side lines ct, where the convex and concave surfaces lcome together, are longitudinally straight, but maybe made .more or less rounded, equally or unequally, as illustrated in Figs. 5 and 6, or acute, as at ot in Figs. 5a and 6a, or, again, if in any instance desired, one edge may be made thin and angular, as at a2, and the other rounded, as at c4 in Figs. 5b and 6b. Generally the form shown in Fig. 5 is preferred, one edge being rounded off on a circle somewhat smaller than that of the other edge, thus meeting a greater variety of Work.

The rounded edges a taper longitudinally from the larger to the smaller end in substantially the same proportions as the convex and concave surfaces, all ofthe surfaces being abrasive or working surfaces and longitudinally converging toward a smaller end without material change in the general transverse contour or cross-section shape except in size thereof, which varies at different positions in the length of the convergent faces.

The larger end B is best squared off ,with its surface substantially perpendicular to the axis of an imaginary cone coinciding with the exterior surface 3, so that it presents a flat surface, on which straight-edged cutters can be sharpened or inward angular forms reached by using its corner S. The smaller end'C may be formed square, as at line m, Fig. 2, or with a iiat beveled end, as at line m or m2, Fig. 3, but is best made with a rounded or spherical surface 7 at the extremity, the inner and outer curved surfaces merginginto eachother by a rounded terminal apex. In the general proportions of this tool the breadth of the end Bis about one-third of the length, and the length may be for ordinary sharpening purposes some six to eight inches, more or less, or as required in anyspecial instance.

VVoodWorking-gouges as manufactured for the trade are among the general forms regularly made in three styles of curve-viz., the quick7 sweep or curve, the medium curve, and the slight curve, these being standard tools. It is my purpose, in accord therewith, to make the transverse curvature vor crescent cross-section of my improved sharpening-tool in quick, medium, and slight curve degrees of modification to meet the requirements for sharpening such curved cutters.

This improved sharpening-tool can be made of any of the various kinds of stone or grit materials, such as are suitable for abrasive or sharpening purposes, either in the natural or artificiallyprepared condition. Preferably they are molded or produced from finelycomminuted corundum, emery, or similar grit and a suitable binding medium in solid form that is, of uniform kind and consistency throughout the entire body-and are rendered hard and permanent by pressure, vitrifying, or other Well-known process similar to that applied in the manufacture of grinding- Wheels.

In some instances it is found desirable to slightly increase the concavity of the inner surface 5 toward the smaller end relatively to the convexity of the outer surface 3, so that while the surfaces both form a true conoidal taper the edges d near the smaller end Will include a greater number of degrees in the concave arc than at the larger end.

By reason of the peculiar construction of the sharpening-tool as herein shown and described I provide a means or instrument suited to the sharpening of gouges, curved cutters, or other round-nose tools of a great variety of sizes and shapes with the single sharpening tool or slip and for both outside and inside edge bevels. Furthermore, I produce a desirable, convenient, and serviceable instrument that has rapid sharpening capacity on this class of work, since the peculiar shape operates to embrace and contact With the rounded cutter in an advantageous and successful manner.

What I claim as my invention, and desire to secure by Letters Patent, is-

l. A sharpening-tool or slip-stone made of abrasive grit material, and comprising arigid longitudinally-tapered body presenting outward and inward curved sharpening-surfaces, and formed approximately crescent-shaped in cross-section at any position in its length.

2. A sharpening-tool composed of abrasive grit material, formed with a longitudinallytapering body that is transversely crescentshaped in cross-section, and having its respective edges formed of different thickness and curvature.

3. A sharpening-tool of an abrasive nature, having a rigid tapered body formed with an abrading outer face transversely convex, and an abradin g inner face transversely concave, said convex and concave faces formed on-relatively different transverse curvatures, and longitudinally diminished in radius of curvature to relatively dierent degrees, toward one endthereof, and affording the conoidal sharpening-faces with relatively increasing concavity of the inner face; for the purpose set forth.

4. A sharpening-tool or slip-stone, composed of grit substance such as described,

and formed in a solid longitudinally-tapered Witness 1n yhand this 4th dayof February,

FRANK A. IIUMPHREY. Vitnesses:

Guns. ll. BURLEIGH, ELLA l). BLENUS. 

